DMARC (Domain-based Message Authentication, Reporting, and Conformance) is an email authentication protocol that allows domain owners to specify how their domains should be authenticated and what to do if an email fails authentication. DMARC can be used to detect forged sender claims by checking the SPF and DKIM records for the sending domain. SPF (Sender Policy Framework) is an email authentication protocol that allows domain owners to specify which IP addresses are authorized to send email on their behalf. SPF can be used to detect forged sender claims by checking the IP address of the sending server against the SPF record for the sending domain.